The unlimited backup plan is not a cloud storage.
Not once did I say it was for storage. All of my replies was from the perspective of backup.
If storage is really a concern, then get a domain + google workspace unlimited storage tier at 20USD/240USD per year.
A cheap domain is like 5-10 sgd for like 10 years. Rounds out to about 340 - 360 SGD per year for unlimited storage. It used to be much cheaper but google recently just crapped over new users. I'm a currently subscriber but am still on the old plan of 12USD/month/user and I'm using this for media storage since these data are perishable and not important to me
For smaller storage like say <1TB and you rarely access it, cloud storage options like backblaze B2 is super ideal as you pay for what you upload/download which is 0.005usd/gb/month and download is at 0.01usd/gb
So let's say you have a 200GB data which you upload, that's 1USD per month. And if you do download it, 2USD per download.
Let's say you upload a total of say, 5GB of changes per month, that's going to add like 0.025 USD per month.
No matter how I see it, both options for storage still beats NAS + HDD since there are maintenance cost to keep in mind(electricity, NAS/HDD going kauput + troubleshooting)
Unless you value privacy/security(they both do support encryption but where they host their DC are hmmmmm) + have a crappy connection which shouldn't be the case since we have one of the cheapest internet in the world. Although I don't deny that local storage is much quicker due to latency.